Please help due today

Chemistry

2 answers:

ki77a [65]3 years ago

5 0

Answer:

For the first one it's no.

On your Second question it's MgS.

Anastaziya [24]3 years ago

3 0

Answer:

the answer for the magnesium sulphate is MgSO4

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Why do we use only a very small flame to heat the Thiele tube when determining the melting point of a crystalline solid?

Strike441 [17]

The Thiele tube which is look like a triangle, used for the determination of melting and boiling point of the solid and liquid sample respectively. The tube consists of high viscous oil. The mouth of the triangle tube consists the thermometer and the sample through a rubber stopper. The tube is always heated in low flame as the heating mechanism of the oil is through convection current process, in which the molecules of the oil heated passes through out the bulk to make a uniform heat of the liquid. The uniform heat of the liquid is necessary to determine the exact melting point of the solid. Also the low heating rate is compulsory so that the rate of convection current be slow. The high heating rate may cause fast convection in the oil and the hot oil can spill out from the tube and may cause an accident.

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A chemist weighed out 49.0 g of calcium. Calculate the number of moles of calcium she weighed out. Be sure your answer has the c

fgiga [73]

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1.22 mol Ca

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3 years ago

6. How many moles of water would require 92.048 kJ of heat to raise its temperature from 34.0 °C to 100.0 °C? (3 marks)

scoray [572]

Taking into account the definition of calorimetry, 0.0185 moles of water are required.

<h3>Calorimetry</h3>

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

Sensible heat is defined as the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).

So, the equation that allows to calculate heat exchanges is:

Q = c× m× ΔT

where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.

<h3>Mass of water required</h3>

In this case, you know:

Heat= 92.048 kJ
Mass of water = ?
Initial temperature of water= 34 ºC
Final temperature of water= 100 ºC
Specific heat of water = 4.186 $\frac{J}{gC}$

Replacing in the expression to calculate heat exchanges:

92.048 kJ = 4.186 $\frac{J}{gC}$ × m× (100 °C -34 °C)

92.048 kJ = 4.186 $\frac{J}{gC}$ × m× 66 °C

m= 92.048 kJ ÷ (4.186 $\frac{J}{gC}$ × 66 °C)

<u><em>m= 0.333 grams</em></u>

<h3>Moles of water required</h3>

Being the molar mass of water 18 $\frac{g}{mole}$ , that is, the amount of mass that a substance contains in one mole, the moles of water required can be calculated as: